As information technologies (IT) advance, an existing or installed IT system might migrate to a new system using one or more new technologies. The migration process may be a gradual one, and a smooth transition from the installed base to the new system with minimal interruption of service may be needed. To minimize the service interruption, the installed base may carry out its normal functions until the new system is ready to take over. A common example of the IT system migration is that an enterprise IT system migrates to a new system that uses a new version of operating system, database, and server computers. In one migration scenario, the IT system migration is a continuous process with a current configuration and a target configuration. When the current system configuration reaches the target configuration, the target configuration becomes a new current configuration, and a new target configuration then becomes the next goal for the new current configuration to reach.
In another IT system migration scenario, the IT system migration may not happen as often as in the other scenario. One of the main goals for IT system migration is to reach a target system state. There may be three sets of system parts or modules that are involved in the system migration: retired parts from the installed base to be decommissioned, reconfigure parts from the installed base to be put in the new system after some reconfigurations or modifications, and new parts to be added to the new system. Thus, the tasks of IT system migration may include decommissioning the retired parts in a specified order to minimize the service interruption, and reconfiguring, modifying, integrating and testing the reconfigure parts and the new parts.